Architecture of a turbomachine with counter-rotating turbine

Abstract

Counter-rotating turbine of a turbomachine extending about an axis of rotation and comprising an inner rotor rotating about the axis of rotation, and comprising at least one inner movable blade rotatably supported by a first shaft, an outer rotor rotating about the axis of rotation in a direction opposite to the inner rotor, and comprising at least one outer movable blade rotatably supported by a second shaft coaxial with the first shaft, the first and second shafts extending axially from upstream to downstream of the turbine, wherein the first shaft is guided in rotation by a first bearing disposed between the first shaft and an upstream casing of the turbine, and the second shaft is guided in rotation by a second bearing disposed between the second shaft and said upstream casing of the turbine.

The invention claimed is: 
     
       1. A counter-rotating turbine of a turbomachine, extending about an axis of rotation, the counter-rotating turbine of the turbomachine including:
 an inner rotor configured to rotate about the axis of rotation, and comprising at least one inner movable blade rotatably supported by a first shaft, 
 an outer rotor configured to rotate about the axis of rotation in a direction opposite to the inner rotor, and comprising at least one outer movable blade rotatably supported by a second shaft coaxial with the first shaft, the first and second shafts extending axially from upstream to downstream of the turbine, 
 a turbine vane frame disposed upstream from the inner rotor and the outer rotor, 
 wherein the first shaft is guided in rotation by a first bearing disposed between the first shaft and the turbine vane frame, and the second shaft is guided in rotation by a second bearing disposed between the second shaft and said turbine vane frame, the counter-rotating turbine comprising an outer casing only extending downstream from the turbine vane frame and at least partially surrounding a blade of the at least one inner movable blade and a blade of the at least one outer movable blade, the outer casing extending axially from an upstream end of the turbine, over a length of less than 50% of the length of the turbine, and the outer casing is radially outward of any other portion of the turbine, and wherein the counter-rotating turbine does not include a turbine rear frame casing. 
 
     
     
       2. The turbine according to  claim 1 , wherein the at least one inner movable blade is rotatably supported by a portion of the first shaft cantilevered from the first bearing, and the at least one outer movable blade is rotatably supported by a portion of the second shaft cantilevered from the second bearing. 
     
     
       3. The turbine according to  claim 1 , wherein the second bearing is disposed between the second shaft and the first shaft. 
     
     
       4. The turbine according to  claim 1 , wherein the first and second bearings are disposed on a same radial plane normal to the axis of rotation. 
     
     
       5. The turbine according to  claim 1 , wherein the first and second bearings are disposed at a median plane of the turbine according to the axis of rotation, such that the first and second bearings are disposed at a center of a length between the blade located furthest upstream along the axis of rotation, and the blade located furthest downstream along the axis of rotation. 
     
     
       6. The turbine according to  claim 1 , wherein the first and second bearings are roller bearings. 
     
     
       7. The turbine according to  claim 1 , wherein the outer casing extending axially from an upstream end of the turbine, over a length of less than 50%, so that a downstream portion of the outer rotor is no longer encased. 
     
     
       8. A turbomachine with counter-rotating fans extending about an axis of rotation and comprising a ducted fan with a cowl annularly surrounding a fan section which includes a first row of fan blades and a second row of fan blades, the first row of fan blades and the second row of fan blades rotating in opposite directions, the turbomachine further comprising a counter-rotating turbine driving the ducted fan, the counter-rotating turbine of the turbomachine including:
 an inner rotor configured to rotate about the axis of rotation, and comprising at least one inner movable blade rotatably supported by a first shaft, 
 an outer rotor configured to rotate about the axis of rotation in a direction opposite to the inner rotor, and comprising at least one outer movable blade rotatably supported by a second shaft coaxial with the first shaft, the first and second shafts extending axially from upstream to downstream of the turbine, 
 a turbine vane frame disposed upstream from the inner rotor and the outer rotor, 
 wherein the first shaft is guided in rotation by a first bearing disposed between the first shaft and the turbine vane frame, and the second shaft is guided in rotation by a second bearing disposed between the second shaft and said turbine vane frame, the counter-rotating turbine comprising an outer casing only extending downstream from the turbine vane frame and at least partially surrounding a blade of the at least one inner movable blade and a blade of the at least one outer movable blade, the outer casing extending axially from an upstream end of the turbine, over a length of less than 50% of the length of the turbine, and wherein the outer casing radially outward of any other portion of the turbine. 
 
     
     
       9. A counter-rotating turbine of a turbomachine, extending about an axis of rotation, the counter-rotating turbine of the turbomachine including:
 an inner rotor configured to rotate about the axis of rotation, and comprising at least one inner movable blade rotatably supported by a first shaft, 
 an outer rotor configured to rotate about the axis of rotation in a direction opposite to the inner rotor, and comprising at least one outer movable blade rotatably supported by a second shaft coaxial with the first shaft, the first and second shafts extending axially from upstream to downstream of the turbine, 
 a turbine vane frame disposed upstream from the inner rotor and the outer rotor, 
 wherein the first shaft is guided in rotation by a first bearing disposed between the first shaft and the turbine vane frame, and the second shaft is guided in rotation by a second bearing disposed between the second shaft and turbine vane frame, the counter-rotating turbine comprising an outer casing only extending downstream from the turbine vane frame and at least partially surrounding the outer rotor, the outer casing extending axially from an upstream end of the turbine, over a length of 15% to 50% of the length of the turbine, and the outer casing is radially outward of any other portion of the turbine, and wherein the counter-rotating turbine does not include a turbine rear frame casing.